(1) Field of the Invention
The present invention relates to the detection of leaks in, for example, the tubes of a steam generator and particularly to ascertaining whether previously found leaks in such fluid conveying conduits have been properly repaired. More specifically, the present invention is directed to leak detectors which may be inserted in, and employed to ascertain the integrity of, fluid conveying tubes which have been repaired by means of inserting sleeves and/or plugs therein. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
(2) Description of the Prior Art
While not limited thereto in its utility, the present invention is particularly well-suited for employment in the testing of repaired steam generator tubes. Steam generator tube degradation is a highly publicized problem, particularly in the nuclear power field. It is often necessary, in order to overcome a leakage problem, to install repair sleeves or plugs in degraded tubes. A general discussion of the installation of sleeves and plugs in steam generator tubes may be found in U.S. Pat. No. Re. 30,802 which is assigned to the assignee of the present invention.
Regardless of the care which has been employed in the installation of a sleeve or plug, steam generator tube repair has occasionally been unsuccessful. When leakage has occurred during operation of the steam generator subsequent to repair, there has previously been no way to determine whether such leakage was caused by faulty installation of the repair sleeve or plug or by an imperfection in the sleeve or plug. This inability to ascertain the cause of leakage of a repaired steam generator tube may be attributed to the fact that there has been no technique in the prior art which permitted the repaired tube, and particularly the sleeves and plugs installed therein, to be readily checked for leakage during installation. The inability to perform a leakage test during plug or sleeve installation results, in part, from the fact that the plugs and sleeves cannot be checked from the secondary side of the steam generator because the steam generator tube may not be perforated.
An example of a connector which may be employed in a prior art leak detector, for sealing the accessible open end of a tube, may be seen by reference to U.S. Pat. No. 3,542,076. In order to employ the patented device, both ends of the tube to be tested must be accessible, the tube must be thin-walled so as to be capable of deformation by the testing apparatus, and a considerable quantity of gas or other fluid is required for the test procedure.